[[Image:FDTD134.png|thumb|320px|EM.Tempo's Periodicity Settings dialog]]
[[Image|:FDTD140(1).png|thumb|320px|Setting a custom plane wave source plane.]][[Image:FDTD139.png|theumbthumb|320px|Placing a field probe above a periodic structure excited by an obliquely incident plane wave source.]]
===Setting Up A Periodic Unit Cell===